Parliament's sleaze watchdog has lambasted MPs for failing to approve tougher rules on their behaviour.

Standards commissioner Kathryn Hudson expressed "grave concern" that changes proposed in December 2012 had yet to be brought before the House.

The measures were intended to tighten controls on lobbying and declaring interests in the wake of a series of controversies.

The cross-party standards committee also insisted the watchdog should be able to investigate "private and personal" behaviour that brings the House into disrepute.

Some believe the latter provision could have been used in the case of former Liberal Democrat Mike Hancock, who has faced no formal censure despite apologising for an "inappropriate and unprofessional" relationship with a vulnerable constituent.

However, Leader of the House Andrew Lansley has been refusing to bring any of the proposals before parliament because he believes MPs would reject the idea of probes into their private behaviour. Similar plans were voted down in March 2012.

Writing in the foreword to her annual report, Ms Hudson said: "I would be failing in my responsibility to the House if I did not express my grave concern that the House still has not been given the opportunity to consider the revisions to the Guide to the Rules proposed by the Committee on Standards and Privileges in December 2012.

"It is extremely disappointing that time has not been found for such a debate, not least because the new rules are considerably clearer on certain issues, including some which have been the subject of inquiries this year.

"If there is disagreement with some of the Committee's proposals, MPs would be free to amend them in debate and leadership may be shown by addressing issues transparently and honestly rather than by avoiding difficult discussions.

Ms Hudson pointed out that the Standards Committee had recently announced a fundamental review of parliamentary sleaze rules.

The inquiry was launched in the wake of a row over the committee watering down the commissioner's findings about Maria Miller's expenses.

"Such proposals may require further revisions of the rules and processes which will take time and should be done carefully and thoughtfully," Ms Hudson said. "In the meantime the draft rules, which await approval, would provide a way of moving in the right direction while consideration is given to the future shape of the process.

"Approval of the Guide would also enable my office to implement some valuable clarifications of the rules before the beginning of the next Parliament, which would assist new MPs."

It is understood that the committee has been insisting the proposals for widening the Code of Conduct to include private behaviour should be considered at the same time as recommendations for tightening lobbying restrictions in the Guide to the Rules.

They argue that if MPs do not like parts of the package, amendments can be passed to strike them out.

However, g iving evidence to its inquiry into the Commons regulatory system earlier this month, Mr Lansley said he wanted to bring the lobbying changes before parliament by themselves.

"I think it is actually the case, the House having reached the conclusion that it did in March 2012, it would be better to proceed on the basis of the Code as it is," he said.

"That allows one to separate the question of the revision to the Guide, because the two things are packaged together and in my view that is not now necessary.

"It would be possible for us to proceed with the revision of the Guide, I would rather that we did.

"Because that would enable us to have, as I think the previous question implied, something that is clearer, that could be in place before the start of the parliament which would be very helpful..."

The Cabinet minister said there was no reason to expect a "different result" on the Code of Conduct issue.

"The ground would have to be prepared if there were to be a different result, and I was not in any position to expect there would be a different result," he said.

"It is not, I have to tell you, in terms of allocating time, my objective to allocate time for a debate that in itself does not move the position forward."